Micro-electromechanical (MEMS) sensors may use microcantilevers to sense physical, chemical, and biological interactions. A microcantilever is a structure that is fixed at one end and free at the other. MEMS fabricated microcantilevers may be fabricated using silicon-based materials.
For example, microcantilever sensors may be used to sense biomolecular interactions as follows. In order to identify particular biological molecules (referred to as target molecules), a surface of a microcantilever may be functionalized with a particular probe molecule, where the probe molecule interacts with the target molecule. For example, in order to detect particular DNA material, a short single-stranded DNA (ssDNA) sequence may be used as a probe molecule for a complimentary ssDNA. Similarly, in order to detect a particular antigen, an appropriate antibody may be used as a probe molecule.
FIGS. 1A and 1B illustrate biological sensing using a microcantilever. Referring to FIG. 1A, a cantilever 100 is fixed at a first end 110 to a substrate 190, and free to move at a second end 120. A region 130 of the cantilever includes one or more probe molecules 140 for sensing target molecules. FIG. 1A shows the cantilever in its undeflected state.
Referring to FIG. 1B, a target molecule 150 may interact with one or more of probe molecules 140, changing the surface stress of cantilever 100 and causing cantilever 100 to bend. The amount by which cantilever 100 bends generally depends on the number of target molecules 150 interacting with probe molecules 140, and may therefore provide a measure of the concentration of target molecules 150. The deflection of the cantilever may be detected using, for example, optical or piezoresistive detection techniques.